Salt glazing and klin for same



c. DRESSLER SALT GLAZ` ING AND KILN Fon SAME Patented Oct. 6, 1,4925. g

UNITED STA coimann imi.

XILNS,

'ras i PATENT OFFICE..

f, omo, assxciioaro vannnrcan :onrssnnn TUN- mc., yor naw roux, n..r.,vajconroaar1onor New Yoan.) i

sur euznliaann mn, ron sana.

I Annalen ma luy y17, semino. 382,602.

To all whom it may-concern.' y

Beit known thatLCNnyAn., a subject of the King f JGrreat Britain, andresident of Cleveland, in the'I county of Cuyahogal and State ofOhio,`have invented certain new and useful 'Im rofvementsun Salt Glazingand Kilns for ame, of whlch the following is a spet'zification.'

My present invention comprises lmprovements in construction and mode ofopera.

tion devised with .the specific-object inr view of firing andl saltglazmgceramic ware m v a continuous tunnel kiln 'havin yfiring', glazingand cooling vzones formed y communieating sections offen elongatedkiln.' chamber through which the ware is moved. l l

Whlle myy improved method of salt glazing may be carried-out in variousforms of tunnel kilns I lrefera'bly employ for the purposes. mule .lrilnof theinternal combustion chamber type disclosed, for example 1n myprior' Patents 1,023,628 and 1,170,428. A characteristic yfeature ofthis type' of kiln is that the heat transfer between the ware and thecombustion chambersb which the ykiln is heated, is wholly ormain y b aconvection current circulationof the iln atmosphere which is heated bycontact. with lthe combustion chambers and imparts heat tothe ware andis therebycooled lIn firing and salt f glazing ceramic ware vin `acontinuous tunnelf'kiln in accordance with the present invention, Imaintaina re ducing atmosphere containing salt vapors in the glazingzone of the kiln chamber which is intermediate the heating up or mainfiring zone and thefcooling zone. v It is highly desirable to preventany flow of ,the zone atmosphere/into the zones or klln'sec-l tions ateither sideof the glazing zone, bef cause of the detrimental eiec't ofthe salt vapors on the combustion chambersin the firing zone and the'cooling ipes inthe cooling zone, and also becauseit'is desirable 'to'maintain i. oxidizing atmospheres in these glazing l reducing gasatmosphere constituents tothe glazing zone, and withdrawing vaporsandgases `thus supplied and not` absorbed by tnc ware, without pas'sin themthrough the kiln zone at either si e of thesalt glazing zone. `Inaddition I maintain pressure conditions in the kiln-which prevent thelazing zone atmosphere from passin into t ekiln zones at yeither side ofthe g azing zone b'y diffusion or yby longitudinal flow, but do notmaterially disturbthe convection current circulation 'in the kiln zonesat the sides of the glazing zone. The featureslof construction andmethod which I have devised fori/this purpose may be employed incarrying out other processes than salt glazing in continuouskilns. f j

The various features of novelty which characterize my invention arepointedl out with particularity inthe claims annexed to and' formingv aart yof this specifica-tion. For a lbetter understanding `of theinvention, however, and the advantages possessed by it. reference shouldbe had to the accompanying drawings and descri tive matter in which Ihave illustrated and escribed a preferred form of my improved tunnelkiln.

Of the drawings:

1, Fig. 1 is a somewhat diagrammatic plan in section of a kiln.

2.` Fio. 2 is a vvertical section of a portion of the kiln shown in Fig.1, taken on the line'2-,2 of Fig. 1,

AndFigs. 3, 4, 5, 6 and 7 are transverse vertical sections takenrespectively, on the iines V13 3, 4 4, 5 5, 6 6 and 7-'7 of The kiln Ashown in the drawings, comprises an elongated chamber of which one endsection A1, serves as aware heating or main firing zone, intermediatesections A2 and A"i serve as a glazing zo'ne, and the other end sectionA* is aware coolin goods enter the kiln at one en of the zone past adoorB which is normally closed, and lleave the kiln at its opposite endpast the normally closed door C. As shownthe goods are moved throu h thekiln on trucks E running on track rai s DA. The heating zoneA of thekiln is laterally enlarged toprovide space for combustion chambers Il),one at each sidev of ther pathway for the zone. The

goods, and for tubular extensions Dz of thev i.

combustion chambers. The combustion chambers and thelr extensions restupon benches A atthe sides of the kiln. The' jacent each gas burner 1san inlet F for air rsup orting combustion. Each inlet Fy lea s from acorresponding air supply ltunnel F extending longitudinally of the kiln.

The su ply of airth1"ough -each inlet F is contro ed by a damper F2. Thecombustion chambers D ,and the general arrangement of the heating upzone of the klln shown is like that commonly employed in the well knownDressler tunnel kiln. It is to be noted4 however that my invention- Vinsome of its aspects is not restricted to the particular kind of muiileheated kiln shown, ut may be carried out in open fire kilns as well asin other types of muftleheated kilns. v The glazing zone sections A2 andA8 have their roofs slightly higher than lthe roof of the heating upzone A1 to provide a gas collecting space of considerable capacity abovethe goods pathway. This gas collecting space is divided intocompartments A7 which are open at their lower ends, by transversebarriers or fiat arches A8. Each of the compartmentsA7 is provided withone orinore stack outlets A opening through its roof. At each side ofthe glazing zone sections A2 and A and in open communication therewithare oneor more chambers A1". As shown the chambers A10 each receivescombustible gas through burner ipes G3 connected Ato the as supply pipesthrou hre y atin valves an l receives air or t e com ustion of the asAfrom the tunnel F through a correspon ing vertical passage F. Each ofthe vpassages F4 is rovided with a regulating damper F5. Sa t or otherglazing agent to be vaporized by the combustion occurring in thechambers A10 is supplied to each of the latter lthrough a correspondingpipe K.

Advantageously, as in the particular construction shown, the roofof thecooling zone A* is elevated to provide a series of air colf lectingcompartments A71 open at their lower endsto the goods pathway andseparated from one another by barriers'or flat arches AaLf vThe air forcooling the ware passing through the zone Aenters the kiln at its exitend as through ports C in the door C. The air ths admitted and heated bycontct with the goods collects in the various compartments A,71 and iswithdrawn from each of the latter, exceptthe`- compartment A immediatelyadjacent the glazlng zone V0f section As by a pipe J. The latter runsvalong the roof of the kiln and is connected` to each of thecompartments beneath it. The end of the pipe J, adjacent the glazingzone is connected to the inlet of a fan I. The latter is connected bypiping H to two deliveryl nozzles H1 opening one into one and the ot erinto the second of the air supply tunnels F. These nozzles draw by anejector action airtoo hot to pass the fans I from the compartment A71immediately adjacent the glazing zone through vertical channels F3 inthe side walls of the kiln. Air delivered by the fan I in excess of theburner requirements may be passed to a drier or otherwise disposed ofthrough a branch ypipe 11.

With the apparatus described, trucks are introduced into the kiln one ata time at regular intervals past the door B. As each truck 'is thusintroduced, the train of cars filling the kiln is advanced a car length,and

a truck with inishedwarethereon is ejectedl from the exit end of thekiln.. Any suitable means may be employed for eriodically pushing thecarsinto the kiln an advancing i the train of cars filling the kiln. Nomeans for accomplishing this are shown, as suitable means forthe'purpose are well known and in commonfuse. As the goods are movedthrough the heating up zone A1 of the kiln, the ware is more or lessgradually and uniformly brought up to the temperature necessary tocompletely mature the Iware. As shown the ware X is sanitary drain ltilestacked two lengths high on the cars,'but it` will be understood, ofcourse, that the invention is applicable to other ware and otherstacking arrangements than that shown. In its passage through theglazing zone section A2 and As of the kiln, the ware is subjected to theaction of the burning gases and vaporized glazing agent passing into thekiln `from the chambers A1". By suitable manip-` ulating of the gasvalves Gf and the air Idampers F5, the amount of gas burnt and thecomposition of the burning gases entering the kiln from the chambersA1ro may be regulated as desired. It is' ordinarily desirable tomaintain a strongly reducing atmosphere in the glazinozone. rl`his canbe done, of course with the apparatus shown by supplying insuiiicientair to the chambers AOfor the complete combustion of the gas supplied tothose chambers b the burners G8. The gases and vapors a mitted to theglazing zone and not absorbed by the ware escape from the kiln throughthe vents A. The suction exerted by the latter on the glazing zone maybe varied by adjusting the dempers A11 applied to the vents A9 as shownin Fig. 5. The distributed outlets for the air by which the ware iscooled i-n the zone A4, makes possible a very `desirable control of thetemperatures in the cooling zone, and the special provision describedfor passing this air into the tunnel F insures the necessary draft outof each of the compartments A7' without subjecting the fan to the `be.of my invention, asset forth in the appendhigh temperature of theA airin the compartments A" immediately adjacent the high temperature sectionof the kiln. l

The apparatus shown was primarily devised for use in the so called saltglazing process in which the glazing agent employed is common salt, thevapors of which unite with the clay ware at its surface and alongsurface fissures to form silicate of soda. Salt glazing is particularlydesirable because of the excellence of the glaze and the relatively lowcost of the glazing agent. The use of such a glazin agent in acontinuous tunnel kiln is possib e only wherein the kiln con` structionand operation is such as to prevent the glazing agent from contactingappreciably with the Walls of the combustion chambers` or other highlyheated portions of the kiln structure which would be injured. ordestroyed by an excessive coating of glazing material. It is highlydesirable to prevent the condensation of salt vapors in the coolingzoneof the kiln.

o prevent the from passing into e firing or coolin I so regulatepressure conditions in th that there will be a slight but continuousdrawn versel of the latter. The air gently flowing influx of air intothe glazing zonejfrom the portions of the kiln chamber at either side ofthe lazing zone. The air thus withrom the end portionso the kiln may besuppliedb leakage around thedoors at the ends of the kiln, or by specialair inlet ports provided for thevpurpose. I so regulate the suctionthrou h the outlets A' that there is a gentle in ux ofair into .theglazing zone from either'end without creatlng longitudinal air currentsvthrough the end portions of the kiln materially .moditying theconvection current circulation in the end portions ofthe kiln chambertransinto t e opposite e'ndsvof the-glazin zone will unite incombustion, with the uc-ing sin the glazing zone with a resultantprouction of carbon dioxide. The end rtlons of the glazing zoneatmosphere willt us con-v sist of streams of gas iowing upward to the`4outlets A and containing more `or less carl' `bon dioxide.v .The` veryexistence in.A these yend streams of carbon dioxide, tends to retard thecombination in combustion ofthe air in the end portions .of thekilnwith. the

reducing gases in the glazing zone atmosvf -pheref In consequence thecombustion currin inregular operation is in no wise exploslve 1ncharacter, and with` the smalll "amount of air 'availablethe combustionis .relatively lnslgrnfcant 1n amountb 'rovlsio'n's While in` accordancewith the of'the statutes; I' have illustrat and Vdescribed the best formof my invention now known to me, it `will be vapparent to those glazingzone atmosphere t each, end o saidv glaz' skilled the art that changesin form may made Without departing fromv the spirit end portion o f thekiln chamber and heating other portions thereof as required'tov glazefire and then cool the ware in its passage through the chamber,maintaining a lreduc'- ing atmosphere containing a -vaporized glazingagent in )a high temperature glazing zone rtion o' the chamber. v

2. he method of glazing ceramic ware which consists in movin the 'ware'through an elongated kiln chamger, cooling an exit end portion of thekiln chamber and heating other portions thereof as required to 'l glazeviire and then, cool the ware in its passage through the chamber, su pling :i vaporized glazing agent toj a iilg rtemperature glazing zoneportion of the' kiln' chamber,

withdrawinggases and vapors from thelasty mentioned n chamber portionand.y sup-l plying airto portions of the kilnchamb'er at l eaehend ofsaid glazing zone portion.

3..The method `of `,salt glazing ceramic ware which consists in movin'the ware through an elongated kiln cham r, cooling an exlt end portionof the kiln chamber and heating other portionsfthereof as 1re uired toglaze-re and then cool the ware 1n its passage through the chamber andmaintainv in'g'an atmospherecontaining salt vapors in a high temperatureglazing zone portion of the chamber.

4. The method of salt glazing 'ceramici Ware which consists vin movinthe ware through an elongated kiln cham r, cooling an eint end portionof the kiln chamber andheatin otherportions thereof as reguirednto gazejreand then cool the 'ware 1n its assage through the chamber,A suply-` ging t vapors Ato a high" vtem rature g azingfzone portionof-thekiln c amber, withdrawing and vapors from the last 'mention kilnchamber portion and supply rtions ofthekiln 'chamber 'at` air to zoneportion. 5. The method of vmaintaining different atmospheresin`successive .communicating zones or sections of an elongated 'kilnchamber 'through which material is' moved l.and in';w hieh.1t'ismainlyheated by convection currents 'of thekil'n atmos here contacting withthe material' andV wit a hot b o'dy or bodies'fat the-side ofthe pathwayfor vthe material, which consists in supplying gaszones or sectionsof'an elongated kiln chamber throu h which material is moved andinwhichit is heated mainly by convection currents of the'kiln atmosphere.contacting with Vthe material and with a hot body or bodies at the sideof the .pathway for the material, which consists in supplying gaseousingredients to the different zones to form the different atmospheresthereof, withdrawing ,gases from an *intermediate zone of said series,and maintaining pressure conditions in said kilns to prevent appreciablelogitudinal gas iiow in the kiln chamber. l

7. In a mule heated kiln the combination with the kiln chamber andmuiiie heating means therefor, of means for supplying ingredients to anintermediate high temperature of said kiln chamber for maintaining areducing atmosphere containing a vaporized glazing agent therein, andgas outlets opening through the wall ofl said chamber to'said zone.

8. In\a mule heated kiln the combination with an elongated kiln chamberand muflle heating means therefor, of combustion chambers opening to thekiln chamber inv a high temperature zone thereof intermediate its ends,means for supplying fuel, air and a vaporizable glazing agentto said.combustion chambers so as to thereby supply a reducing gas atmospherecontaining the glazing agent in a vaporized form to said zone, and gasoutlets opening through the wall of the kiln chamber to the glazing zonevportion thereof.

" 9.y The combination witha tunnel kiln comprising a heating up zone, aYcoolin zone. and an intermediatey glazing zone, an having combustionchambers 1n said heating up zone and cooling conduits in said coolingzone, of combustion chambers opening into the glazing zone portion ofthe kiln chamber, gas outlets formed in the kiln chamber wall andopening to the glazing zone portion of the kiln chamber, means supply.ing fuel and a vaporizable` glazing agent to the last mentionedcombustion chambers, means supplying fuel to the first mentionedcombustion chambers, and means for passing air through said coolingconduits into all of said combustion chambers.

10. A tunnel kiln provided with a main stack or fan and also having anauxiliary stack or fan independent thereof by which special gases andvapors which have been introduced into the kiln for special purposes maybe removed therefrom without resort being had to the means for inducingthe main draft.

11. A tunnel kiln provided with a main stack or fan and also having anauxiliary stack or fan independent thereof acting on the firing zone ofthe kiln whereby special gases and vapors which have been Introuced intothe kiln for s ecial purposes may be removed ifromlthe ring zone withoutresort being had to the means for inducing the main draft before saidgases or vapors have the opportunity of coming in contact with ware 1nother parts of the kiln.

Signed at Cleveland, in the countyof Cuyohoga and State of Ohio this12th day of May A. D. 1920.

CONRAD DRESSLER.

